A Half-Day Workshop by Two Experts From IITs On Design and Development
of Passive and Active Microwave Metamaterial Absorbers
December 18, 2019 | 2 pm to 6 pm | Narayani Heights Hotel (Conference Venue)
Electromagnetic (EM) wave absorbers have drawn significant research interest
owing to their widespread applications such as radar cross section reduction,
stealth technology, EM interference, EM compatibility, wireless communication,
and so forth. However, conventional microwave absorbers are mostly limited to
minimal thickness of one-quarter wavelength and inadequate for specific band
applications due to constant medium parameters; further, they are usually fragile,
bulky, and have large surface mass density. Therefore, it is difficult to implement
them in various practical applications. With the advent of metamaterial approaches,
absorber structures can be made not only ultra-thin, but also near-unity absorption
can be achieved over different frequency bands including microwave and optical
frequencies ranging from terahertz to infrared. These metamaterial absorber
structures are generally composed of a periodic array of top metallic pattern
and ground metal plane separated by a dielectric substrate.
Typically, metamaterial absorbers based on copper/metal microprinting technologies
are narrow-band in nature. Using this technology, various single, double and multi-
band absorbers have been reported in literature. But for stealth applications,
broadband absorption over entire microwave bands, such as the C, X and/or Ku bands,
is necessary. Single- and multi-band absorbers are based on resonating structures,
where absorption primarily occurs through dielectric loss. On the contrary, broadband
absorbers can be realized by appropriately depositing resistive and conductive
patterns on a substrate. Lumped resistors, resistive sheets, and resistive paints
are the principal sources of ohmic loss behind wideband absorption.
A passive absorber, made from resonating structure and/or resistive material,
exhibits fixed reflectivity characteristics, and sometimes have limited applications.
An active absorber, in contrast, has reconfigurable properties owing to external
stimuli. A switchable active absorber can serve the purpose of an absorber as well
as a reflector just by changing the bias voltage of the design. A tunable absorber,
operating in a wide frequency range, may replace a broadband absorber in several
applications. Varactors and p-i-n diodes are generally used in electronically
regulated active absorber designs, due to their small switching speed, large tuning
range, compact size and low cost.
This workshop will describe in-detail about metamaterial absorbers and their
associated mechanisms. Various narrow-band and wideband passive absorbers will be
discussed in terms of their resonant frequencies, equivalent circuit modelling,
surface current distributions, parametric variations, and measurement procedures.
Subsequently, active absorbers will be explained by showing their simulation set ups,
biasing configuration, diode characterization, and practical realization.
The content of the workshop has been carefully designed such that the researchers
from various microwave backgrounds can get widely benefitted through attending the
1. Dr. Kumar Vaibhav Srivastava, IIT Kanpur
2. Dr. Saptarshi Ghosh, IIT Indore